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Moving parts on the trailer need maintenance too

By on April 30, 2012

Last issue we talked about the importance of lubrication maintenance in the tractor, but it’s just as vital for the trailer. Proper lubrication keeps your trailer in good working condition and prevents high operating costs resulting from premature component wear. It will also help you avoid a failed DOT inspection. June is Roadside Inspection Month, and one of the red flags for an inspector is spotting oil where there should be no oil on a trailer.

Any chance that your vehicle has a leak is cause for concern, so during regularly scheduled trailer PMs your wheel seals must be inspected to ensure they are not leaking. A leak will put a vehicle out of service and can put a driver in danger.

Any fluid on brake shoes is cause for concern. A leaking wheel seal will wash an area clean on the inside of the hub to the point that the brake shoes are negatively impacted or saturated. High temperatures and friction can lead to a fire on the wheel end in a hard braking situation or a long braking demand, such as moving down a steep grade. Saturated brake shoe linings can lessen brake performance.

Be diligent in your pre-trip inspection. There is an important distinction between a slight seep and a leak. Some seepage is normal in older trailers, and that won’t put you out of service. But if you have a new trailer and notice seepage around the seals, have a qualified technician investigate further.

Additional focus must be exercised in regards to s-cam seals. It is important that lubrication reaches the pivot points of the s-cam, and it is equally important to keep the lube in this location as long as possible. Be certain your maintenance provider keeps a close eye on all grease and oil seals, but pay special attention to those s-cam seals. When lubricating s-cam bushings, old grease, contamination and water must be purged visibly from the s-cam bushing seals.

The right schedule

Trailers are sometimes a difficult asset to maintain because many operations are drop and hook. Some of these trailers tend to fall between the cracks or just get missed during the PM scheduling process. To complicate the situation, intervals may need to be adjusted based on the duty-cycle of the trailer. Going off-road regularly will expose the trailer to more dust and contamination, so maintenance intervals should be more frequent. City driving, with its constant stop-and-go driving, means more brake applications and requires shorter maintenance intervals.

Finally, let’s not forget the hub and bearings. During a trailer’s scheduled PM, the oil in the hub must be inspected. It is critical to check the oil level and the condition of the oil. A good practice is to take a magnet and run it through the oil in the hub periodically. If you find metal on the magnet, additional steps must be taken. This can be a little tricky because many times the magnet will detect very tiny silver particles, which may be mistaken as normal, but in reality are bearing material flaking, which is indicative of a pending catastrophic failure. Discoloration of the fluid is another clue that bearing damage has occurred or contamination has entered the hub area. Both conditions will require additional inspection and repairs.

If it moves, lube it

Lubricants improve the efficiency and extend the life of mechanical components in your vehicle by removing

friction, heat, corrosion and by flushing contaminants out from moving parts. Many mechanical failures ultimately are shown to be linked to poor lubrication practices. Consequently, utilizing the right lube at the right time in the right place is key to the longevity of your equipment.

Homer Hogg, Senior Technical Trainer for TA and Petro, has worked as a truck technician for 30 years. He is a Daimler Certified Trainer and a member of the Nashville Auto Diesel College Hall
of Fame.

Homer Hogg’s “Maintenance Matters” airs on the Dave Nemo Show (Road Dog Trucking, SiriusXM 106), 8 a.m. ET, the first Thursday of each month.

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